The long term goal of this research is to utilize vesicles and other three-dimensional assemblies of phospholipids to mediate the synthesis of novel biomaterials designed for skeletal tissue reconstruction. Our general strategy for accomplishing this goal is to entrap calcium ions within lipid vesicles, and exploit the lipid bilayer membrane of the vesicles to physically isolate entrapped calcium from extravesicular ions. The segregation of the calcium and phosphate ions by the vesicle membrane allows highly supersaturated conditions to exist while at the same time preventing mineral formation. in preliminary experiments we have shown that temperature-dependent changes in the barrier properties of the vesicle membrane can be exploited to release entrapped calcium, which reacts with phosphate to form mineral in-situ. The major thrust of this application is the utilization of unique polymerizable phospholipids that form three dimensional organic scaffolds from vesicle precursors. We hypothesize that these phospholipid constructs can function as mineral delivery vehicles and that the polymerizable lipid can be assimilated, along with mineral, into new composite biomaterials. This unique approach to in-situ composite formation could be used as a liposome-containing gel, paste, or solution which forms composite rapidly upon warming from ambient to body temperature. medical and dental applications of this technology include th remineralization of incipient caries, treatment of hypersensitive dentin, and as a bone substitute material.